The present disclosure relates to a fuel supply device for supplying fuel to an engine.
A fuel pump in a fuel tank is connected to an associated engine via a fuel line. The fuel pump supplies fuel from within the fuel tank to the engine, and the engine consumes the fuel. A return passage branches off from the fuel line and a reduction valve is provided in the return passage. When the amount of fuel consumed by the engine is small, the reduction valve opens to return a part of the fuel fed from the fuel pump through the return passage back into the fuel tank.
A fuel pump disclosed in Japanese Laid-Open patent publication No. 2008-255872 is provided within a sub-tank disposed within a fuel tank. Due to this arrangement, fuel remains in the sub-tank even when fuel in the fuel tank is unevenly distributed. Consequently, the fuel pump can supply fuel from the fuel tank to the engine without being affected by the unevenly distributed fuel. In this arrangement, both the fuel pump and the reduction valve are disposed within the sub-tank.
The reduction valve generates heat as it operates. The generated heat of the reduction valve may in turn generate fuel vapors (hereinafter, referred to as vapor) around the reduction valve. As a result, the vapor may be mixed into fuel before it is sucked into the fuel pump. When the liquid fuel with mixed vapor is sucked in the fuel pump, the amount of fuel discharged from the fuel pump may be reduced by the amount of the mixed vapor. As a result of the heat and associated vapors generated by operation of the reduction valve, the fuel pump may not be able to supply the necessary amount of fuel for and to the engine.
Conventionally, a structure capable of preventing the generation of vapors near a functional component from being sucked into the fuel pump has been desired for a fuel supply device, wherein the fuel device includes a fuel pump arranged in a sub-tank within a fuel tank and the functional component arranged around the fuel pump, wherein the functional component generates heat when it operates, similar to the reduction valve.